Fluorinated acyl azides



United States Patent 3,418,341 FLUORINATED ACYL AZIDES Raymond J. Shozda, Wilmington, Del., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware No Drawing. Filed Aug. 14, 1964, Ser. No. 390,772 9 Claims. (Cl. 260-349) The present invention relates to new organic azide compounds and to methods for their preparation.

Azides have been used in industry as gas-generating compounds, polymerization initiators, chemical intermediates, and for other uses. This invention provides a new group of azides which can be employed in many such uses. This invention also provides a process for preparing the aforementioned new azides as well as others of the rare fluorine-containing azide family.

The new compounds of the present invention have the structure RCON wherein R is selected from the group consisting of F- and F N. The process of this invention is a process for preparing fluoroazides which process comprises contacting molecular fluorine with at least one compound selected from the group consisting of CO(N H NCON and at a temperature below the decomposition temperature of said compound in an inert solvent.

As indicated above, the temperature of the fluorination reaction is below that at which the reaction becomes so vigorous that serious decomposition begins, yet sufiiciently high so that the reaction proceeds at an appreciable reaction rate. The precise reaction temperature varies somewhat depending upon the particular compound being fluorinated. With carbonyl azide, the temperature usually ranges from to C. and, preferably, 0 to 30 C. With carbamazide, the reaction temperature is usually -20 to 50 C., and, preferably, 20 to C., while with 2-azidohexafluoro-2-propanol, a reaction temperature of about to 30 C. and, preferably; 30 to 25 C. is used.

The fluorine gas either alone or in admixture, for example, in amounts of 5 to 50% by volume, with inert gas, for example, nitrogen, argon, helium, etc., is introduced into a solution of the compound to be fluorinated in inert solvent, for example, by a sparge, distributor plate, or other conventional gas-liquid reaction devices. Examples of solvents include halogenated solvents such as halohydrocarbon oil; perfluorokerosene; perfluoro-Z-butyltetrahydrofuran; Freon fluorocarbon products such as dibromotetrafluoroethane, trichlorotrifluoroethane, tetrachlorodifluoroethane; perfluorotributylamine; methylene chloride.

The concentration of the compound being fluorinated as well as the rate of addition of fluorine also vary somewhat depending upon such compound. In general, the concentration of the compound being fluorinated varies from 0.1 to 15% and fluorine is introduced at a rate of about from 4 to part of fluorine per part of compound per minute. With carbonyl azide, the concentration is usually about from 0.1 to 10% and, preferably 0.3 to 5% by weight and the addition rate is 4 to /10 Part of fluorine per part of carbonyl azide per minute. With carbamazide, the concentration is usually 0.2 to 10% and, preferably 0.4 to 5% by weight, while the fluorine addition rate is to part by weight of fluorine per part of carbamazide per minute. With Z-azidohexafluoro-2-propanol, the concentration is usually about 0.4 to 10% and, preferably 2 to 7% by weight, while the rate of addition is usually of from 3,418,341 Patented Dec. 24, 1968 4 to & part of fluorine per part of 2-azidohexafluoro-2-propanol.

The resulting fluorinated products, FCON F NC0N and CF CON can be recovered by conventional means such as distillation.

In addition to the foregoing procedures, the new products of this invention also can be prepared by replacement of acyl chlorides thereof, i.e., FCOCl and F NCOCI by azido groups.

This replacement of acyl chloride by azido groups is carried out by treating the acyl chloride with an azide salt of an alkali or alkaline earth metal in a diluent. Such azide salts as silver azide, sodium azide, potassium azide, ammonium azide, or lithium azide are useful but lithium azide is particularly useful because of its solubility in organic solvents. The replacement is carried out at a temperature of about from l0 to 60 C. but preferably from 10 to 30 C. The molar ratio of azide salt to acyl chloride used is about from 1/ 2 to US but preferably from 1/1 to 2/ 1.

The invention is illustrated in more detail by the following examples which, however, are not intended to be limiting. Parts and percentages, where given, are by weight unless otherwise indicated.

EXAMPLE 1 A solution of 3 parts of carbonyl azide (CO(N in 300 parts of perfluoro 2-butyltetrahy'drofuran is stirred in a glass container irradiated by a sunlamp positioned seven inches above the container. A gas stream of /20 nitrogen-fluorine by volume is bubbled through the liquid at such a rate as to give a flow of 0.034 part of fluorine per minute for 8 hours. The temperature is maintained below 25 C. The exit gases are passed through a trap cooled to 80 C. After 8 hours the material collected in the trap is fractionally distilled to give FCON Its vapor pressure-temperature curve is determined by standard methods and is described by the equation log P Relative abundance Assigned ion The characteristic peaks of the infrared spectrum of FCON determined as a gas at 10 mm. pressure are:

N group-4.5 and 8 microns C O group-5.45.45 micron doublet CF group8 micron region (overlaps N peak) FCON is a dehydrating agent for chromatographic columns and for other enclosed areas. This is demonstrated by condensing together 89 parts of FCON and 17 parts of Water. After holding the temperature at 25 C. for 3 hours the contents of the vessel are analyzed by infrared. No water or FCON are detected. For drying chromatographic columns, FCON is passed through the column until it is detected at the outlet of the column. The column is then dry.

3 EXAMPLE 2 FCOCl (35.4 parts) is condensed in an evacuated container containing 25 parts of sodium azide and 400 parts of perfiuorokerosene. The container is warmed to room temperature and stirred for 22 hours. A 0.01 aliquot of the product is passed through a gas chomatographic column (12 ft. x A in. column of 20% Kel-F ester on firebrick) to separate 0.104 part of FCON (45% yield).

EXAMPLE 3 A mixture of 1 mole of F NCOCl, 1 mole of AgN and 1 part of perfluorokerosene is stirred 16 hours at room temperature. The volatiles are distilled through traps at C., 80 C. and 196 C. The 80 C. trap contains mainly F NCON (72% TABLE II.MASS SPE('YIRfijhg1 OF DIFLUOROCARBAMAZ- Relative abundance dspecgrum corrected for small amounts of CO BN HNFg, FCONQ}, an H;

i Rearrangement ion or trace of fluorocarbon.

The characteristic peaks of the infrared spectrum of F NCON determined as gas at mm. pressure are:

N group-peaks at 4.57 and 8.1 microns C=O grouppeak at 5.55 microns NF group-four peaks between 10 and 11.5 microns The utility of F NCON as an initiator for the polymerization of tetrafluoroethylene is shown as follows:

A Hastelloy-lined shaker tube is charged with parts of perfiuoro-1,3-dimethylcyclobutane, closed, cooled to 70 .C. and evacuated. Tetrafluoroethylene (15 parts) and F NCON (0.04 part) are added to the tube which is then warmed slowly. On reaching 130 C. the pressure rises rapidly from 460 p.s.i.g. to 500 p.s.i.g. Within three minutes the pressure drops to 360 p.s.i.g. and in another 19 minutes falls to 270 p.s.i.g. Over the next 3.5 hours at 130 C. the pressure slowly falls to 215 p.s.i.g. After cooling and venting the tube is opened. A waxy polymer of tetrafluoroethylene (10 parts) melting over 300 C. is removed from the tube.

A control run made in the same manner but with no F NCON present gave no polymer.

EXAMPLE 4 A stream of fluorine, 0.038 part/minute diluted with nitrogen (0.152 part/min), is passed through a stirred mixture of 2 parts of parts of NaF and 175 parts of Halocarbon oil (completely halogenated chlorofluoro carbons), for 1.75 hours at 28-37" C. The efiluent gases are trapped at 63 C. The trapped liquid is distilled under a good vacuum to give a mixture of FCON (30%) and F NCON (70%). The FCON is distilled off at 20" C. under vacuum to give 0.2 part of F NCON The boiling point is estimated to be about 60 C. but sample decomposition at this temperature prevents accurate determination. The P NMR spectrum shows a single broad peak at 1928 c.p.s.; 56.4 megacycles versus Freon-11 fluorocarbon solvent as an internal reference.

1' EXAMPLE 5 Fluorine (0.015 part/min.) and nitrogen (0.152 part/ min.) are passed through a mixture of 1.3 parts of 2- -azidohexafiuoro-2-propanol and 45 parts of Halocarbon oil for minutes at ice bath temperature. The 01T- gases are passed through a 80 C. trap. The trap contains 15% CF CON after the reaction (about 0.3 part).

The mass spectrum is as given below.

TABLE Ill-MASS SPECTRUM OF CFsOONa M/e Ion Relative abundance (percent 139 CF3CON3+ 0.?

The characteristic peaks of the infrared spectrum of OF3CON3 are:

N group4.5, 4.61 and 8.05 or 8.5 microns 'C O group-565 microns CF -8.05 or 8.5 microns and 9.63 microns The vapor-pressure-temperature curve of CF CON is determined by standard means. It is described by the equation The AH =7860 cal/mole and the Tronton constant 24.5 cal./ degree. CF CON is useful as a chemical intermediate and as a cocatalyst for the anionic polymerization of e-caprolactam as described in U.S. Patent 3,017,- 391.

45.2 parts of dry e-caprolactam are melted at C. and sparged with Seaford grade nitrogen (350 cc./min.) for 10 minutes. 0.96 part of NaH (50% active, 50% mineral oil) are added and sparging continued for 5 minutes. Next, a solution of 0.250 part of trifluoroacetyl azide in 1.1 parts of dry benzene under 5 p.s.i. nitrogen pressure in a cylinder is added to the monomer melt. In one hour at 150 C., the reaction mass has turned solid. The polymer is water insoluble.

A similar run but omitting the azide does not solidify after 2. hours.

I claim:

1. Compound having the structure RCON wherein R is selected from the group consisting of F and NF 2. The compound, FCON 3. The compound, F NCON 4. A process for producing FCON which comprises contacting molecular fluorine with CO(N at a temperature below the decomposition temperature of CO(N in an inert solvent. v

5. The process of claim 4 which is conducted at a temperature of about from 20 to 30 C.

6. A process for producing F NCON which comprises contacting molecular fluorine with H NCON at a tem- 5 6 perature below the decomposition temperature of 9. The process of claim 8 which is conducted at a tem- H NCON in an inert solvent. perature of about from -50 to 30 C.

7. The process of claim 6 which is conducted at a temperature of about from 20 to 50 C. References Cited 8. A process for producing CF CON which comprises 5 contacting molecular fluorine with UNITED STATES PATENTS (|)H 2,617,817 11/1952 Ahlbrecht et al. 260453 OTHER REFERENCES N3 10 Chemical Abstracts 43: 6793 c (1949). at a temperature below the dccompositlon temperature JOHN D. RANDOLPH, Primary Examiner. (3. M. SHURKO, Assistant Examiner. CFaC-CF3 15 1 US. Cl. X.R.

in an inert solvent 204 1ss; 2524, 194; 26078, 92.1 

1. COMPOUND HAVING THE STRUCTURE RCON3 WHEREIN R IS SELECTED FROM THE GROUP CONSISTING OF -F AND -NF2. 